Activation of the pre-supplementary motor area but not inferior prefrontal cortex in association with short stop signal reaction time--an intra-subject analysis.

Chao HH, Luo X, Chang JL, Li CS - BMC Neurosci (2009)

Bottom Line:
The pre-supplementary motor area (preSMA), which shows greater activity in individuals with short as compared to those with long SSRT, plays a role in mediating response inhibition.In contrast, the right inferior prefrontal cortex (rIFC) showed greater activity during stop success as compared to stop error.By comparing regional brain activation between the two sessions, we confirmed greater preSMA but not rIFC activity during short as compared to long SSRT session within individuals.

Affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA. herta.chao@yale.edu

ABSTRACT

Background: Our previous work described the neural processes of motor response inhibition during a stop signal task (SST). Employing the race model, we computed the stop signal reaction time (SSRT) to index individuals' ability in inhibitory control. The pre-supplementary motor area (preSMA), which shows greater activity in individuals with short as compared to those with long SSRT, plays a role in mediating response inhibition. In contrast, the right inferior prefrontal cortex (rIFC) showed greater activity during stop success as compared to stop error. Here we further pursued this functional differentiation of preSMA and rIFC on the basis of an intra-subject approach.

Results: Of 65 subjects who participated in four sessions of the SST, we identified 30 individuals who showed a difference in SSRT but were identical in other aspects of stop signal performance between the first ("early") and last two ("late") sessions. By comparing regional brain activation between the two sessions, we confirmed greater preSMA but not rIFC activity during short as compared to long SSRT session within individuals. Furthermore, putamen, anterior cerebellum and middle/posterior cingulate cortex also showed greater activity in association with short SSRT.

Conclusion: These results are consistent with a role of medial prefrontal cortex in controlled action and inferior frontal cortex in orienting attention. We discussed these findings with respect to the process of attentional monitoring and inhibitory motor control during stop signal inhibition.

Figure 3: Regional brain activation in short as compared to long stop signal reaction time (SSRT): BOLD activations in the putamen, middle/posterior cingulate cortex and cerebellum in association with short as compared to long SSRT. Color bar indicates voxel T value.

Mentions:
To identify potential new brain regions with this intra-subject analysis, we compared short and long SSRT sessions for the whole brain using a paired sample t test. The results showed that, compared to long SSRT, short SSRT session was associated with greater activation in the right putamen (x = 28, y = -4, z = 0, voxel Z = 4.24, 5,184 mm3), the medial aspect of the central lobule in the anterior cerebellum, part of the cerebellar vermis (x = -4, y = -44, z = -12, voxel Z = 4.09, 3,008 mm3) and the middle/posterior cingulate cortex (x = 8, y = -12, z = 40, voxel Z = 3.74, 1,792 mm3), at a threshold of p < 0.001, uncorrected, and 20 voxels in the extent of activation (Figure 3). In contrast, no brain regions showed greater activation during the long as compared to the short SSRT session.

Figure 3: Regional brain activation in short as compared to long stop signal reaction time (SSRT): BOLD activations in the putamen, middle/posterior cingulate cortex and cerebellum in association with short as compared to long SSRT. Color bar indicates voxel T value.

Mentions:
To identify potential new brain regions with this intra-subject analysis, we compared short and long SSRT sessions for the whole brain using a paired sample t test. The results showed that, compared to long SSRT, short SSRT session was associated with greater activation in the right putamen (x = 28, y = -4, z = 0, voxel Z = 4.24, 5,184 mm3), the medial aspect of the central lobule in the anterior cerebellum, part of the cerebellar vermis (x = -4, y = -44, z = -12, voxel Z = 4.09, 3,008 mm3) and the middle/posterior cingulate cortex (x = 8, y = -12, z = 40, voxel Z = 3.74, 1,792 mm3), at a threshold of p < 0.001, uncorrected, and 20 voxels in the extent of activation (Figure 3). In contrast, no brain regions showed greater activation during the long as compared to the short SSRT session.

Bottom Line:
The pre-supplementary motor area (preSMA), which shows greater activity in individuals with short as compared to those with long SSRT, plays a role in mediating response inhibition.In contrast, the right inferior prefrontal cortex (rIFC) showed greater activity during stop success as compared to stop error.By comparing regional brain activation between the two sessions, we confirmed greater preSMA but not rIFC activity during short as compared to long SSRT session within individuals.

Affiliation:
Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA. herta.chao@yale.edu

ABSTRACT

Background: Our previous work described the neural processes of motor response inhibition during a stop signal task (SST). Employing the race model, we computed the stop signal reaction time (SSRT) to index individuals' ability in inhibitory control. The pre-supplementary motor area (preSMA), which shows greater activity in individuals with short as compared to those with long SSRT, plays a role in mediating response inhibition. In contrast, the right inferior prefrontal cortex (rIFC) showed greater activity during stop success as compared to stop error. Here we further pursued this functional differentiation of preSMA and rIFC on the basis of an intra-subject approach.

Results: Of 65 subjects who participated in four sessions of the SST, we identified 30 individuals who showed a difference in SSRT but were identical in other aspects of stop signal performance between the first ("early") and last two ("late") sessions. By comparing regional brain activation between the two sessions, we confirmed greater preSMA but not rIFC activity during short as compared to long SSRT session within individuals. Furthermore, putamen, anterior cerebellum and middle/posterior cingulate cortex also showed greater activity in association with short SSRT.

Conclusion: These results are consistent with a role of medial prefrontal cortex in controlled action and inferior frontal cortex in orienting attention. We discussed these findings with respect to the process of attentional monitoring and inhibitory motor control during stop signal inhibition.